General requirements
1, the bidding unit (if bidding for the agent) must provide by the foreign factory (heat exchanger and heat exchanger unit manufacturing) issued by the overall unit of the project's authorisation.
2, the design of the integrated heat exchanger unit, the unit's main components (plate heat exchanger, circulating charge pump, frequency converter, electric valve actuator, etc.) are imported brands, the unit's other major accessories should be joint ventures or domestic high-quality brands, and have more than three years of supporting history.
3, the equipment, whether in the delivery, storage and installation should be taken during the correct protection facilities, especially the heat exchanger heat exchanger piece and the surrounding seals, should ensure that the equipment is not damaged in any case.
4, heat exchanger of the water pipe connection port, before the connection shall take appropriate protective measures to properly cover, in order to prevent the entry of foreign objects.
Unit component requirements
1, complete sets of heat exchangers include:
Heat exchanger unit contains plate heat exchanger, circulating water pump, electric valve, electric control cabinet, various valves, filters, soft connections, piping fittings, power distribution wiring, PLC operation and control, touch screen, automatic control instrumentation, control software, equipment base.
2, in order to ensure the integrity of the project, and to meet the use of the requirements, the bidder should provide the equipment can be normal and effective use of all necessary accessories, equipment and services.
3、 Design conditions
Under the design conditions provided, the selection of heat transfer coefficient of plate heat exchanger, the selection and calculation of unit equipment, piping, valves, etc. shall be based on the specific requirements of the technical terms and conditions for each heat exchanger unit parameters. Unit in normal operation, the medium flow rate in the pipeline must be less than 2.2m / s.
4, plate heat exchanger
4.1 Technical requirements
(1) Must provide professional design parameter table.
(2) Plate heat exchanger must be parallel flow, single flow design, do not accept the cold, hot side of the cross over.
(3) Plate material (304 stainless steel), thickness ≥ 0.5mm, pad material (EPDM), and bonding-free pad.
(4) Guide rods and pillars are made of high-quality carbon steel or aluminium alloy and other sturdy metal materials, and spray paint or other methods of anti-rust treatment.
(5) The frame fixing plate and compression plate are made of Q235-B ordinary carbon steel and treated by shot blasting and rust removal, painting and drying.
(6) Clamping bolts are made of 45# high-quality carbon steel, and the surface is treated with antirust treatment; all bolts shall have one-way self-locking design and be equipped with protective sleeve.
(7) plate heat exchanger assembly is complete, should be hydrostatic test, the test pressure is 1.3 times the working pressure, and issue a report as a random document.
(9) Each heat exchanger to compensate for heat exchange due to scaling and affect the effect, shall provide more than fifteen per cent of the heat transfer area, and the frame should be left (15%) of the plate capacity.
(10) The heat transfer coefficient is required to be not less than 3500 W / (m2 * ℃), not higher than 5500 W / (m2 * ℃), the project equipment selection parameters in accordance with the 4000 W / (m2 * ℃) calculation.
(11) heat exchanger large flow side pressure loss of less than 50Kpa.
5, electric control valve
Electric control valve using Danfoss, Samson or Spisak brand (taking into account the unity of my company, preferred Danfoss brand). Requirements for the same brand of original valve body, can not choose to mix the valve.
5.1 Valve body
Electric control valve valve body structure for the straight stroke of the single-seat valve body, pressure level PN16, its flow capacity Kvs value and calibre must meet the requirements of the process flow. Valve right degree ≥ 0.5.
Flow characteristics for equal percentage characteristics;
Flange connection;
Leakage rate ≤ 0.05% of Kvs value;
Control range > 50: 1;
The valve body is normally open to ensure uninterrupted heat supply when the driver is damaged or removed;
The maximum closing differential pressure meets the design requirements.
Valve body material is grey cast iron or ductile iron; stem material is stainless steel; sealing material is PTFE or EPDM.
5.2 Driver
The driver is driven by two-way motor, the gear is metal gear, the driver should have overload protection;
It can be operated mechanically and manually without power failure;
The signals can be divided and controlled;
Positive/reverse selective control;
With valve travel self-test function to reduce commissioning time;
The control signal is a standard analogue signal, 0(2)-10V/0(4)-20mA optional;
With valve position feedback function, the feedback signal is 0/2-10V;
The control mode is analogue control and three-point control optional;
Driver and valve body must be the same brand.
5.3 Controller: Danfoss, GE, Schneider.
Controller dedicated to district heating system, programmable and has a remote communication function. Working environment temperature 0~55℃; storage temperature -20~85℃.
(1) Data monitoring
Measurement of analogue quantities (e.g. temperature, pressure, flow etc.), digital quantities (e.g. pump status, high and low limits of water level) and measurement of heat, water flow consumption and pump energy loss. The controller is programmed for PID operations and logic operations.
(2) Communication function
The controller itself has a communication serial port to connect with field instruments, inverters, heat meters, touch screens, etc. The built-in network card has a RJ45 network interface. To achieve the communication function, the open communication protocol supports modbus RTU, modbus-TCP/IP, Lon-Works, BAC-net, M-bus and other protocols. The controller can transfer the status of the equipment from the base station to the monitoring centre for the purpose of analysis, and the controller can independently control the system operation and accept the commands of the monitoring centre.
(3)Calendar and clock function
With real-time clock function. The controller has a calendar and a clock (year, month, day, minute, second) to perform the timing control function of the system clock of the control centre.
(4) Display and operation functions
Controller can be equipped with Chinese and English backlit LCD touch screen, the display is mounted on the panel of the control cabinet. The operation panel can display the operation process diagram of the heat exchanger station, the switch of the valve and the start/stop status of the pump. The operator is able to control all the equipments in the heat exchanger station through the panel, including the modification of operating parameters.
(5) Control and adjustment
The controller is freely programmable and can realise all measurement, control and conversion functions.
(6)Time division of heat supply
The controller is able to establish a time programme to control the temperature of the secondary water supply in accordance with the time programme, a function that can help us save energy in public buildings during periods of non-work.
(7)Data upload
Through standard protocols, the controller can accept commands from the SCADA system to adjust and update data.
6, water pumps
6.1 Pump technical requirements
Water pump brand Grundfos, Wilo, Konmacs and other imported brands.
Circulating water pump for three-phase motor (380V 50Hz) drive vertical pipeline pump. The use of flexible joints and pipeline connections. Make-up water pump for three-phase motor (380V 50Hz) drive vertical multi-stage centrifugal pump, threaded connection. Circulating water pump and make-up water pump are frequency conversion speed control.
In order to maintain efficient operation of the pump in the operating range, the pump working point selection needs to be as close as possible to the pump's best efficiency point.
The appearance of the pump should be beautiful and smooth, no scratches and rust spots, the anti-corrosion layer should be uniform, no bubbles and flaking phenomenon. All cast iron parts should be treated with epoxy resin electrophoresis to improve the corrosion and abrasion resistance and prolong the life of the pump.
Mechanical seals are made of well-known brands such as German Borgmann and other original manufacturers, and the manufacturer should promise to inspect and replace the mechanical seals without moving the pump casing and the inlet and outlet pipelines.
The motor should be squirrel cage induction motor. The adopted standard must be higher than China Y series standard. The protection class of the motor is IP55.
The overall design and production of the pump should comply with the relevant European standards, and through the Chinese energy-saving product certification.
6.2 Electrical Technical Requirements
(1) Frequency conversion cabinet technical requirements Frequency conversion control part requires the bidder to make control scheme and secondary wiring diagram. The main components should be ABB, Schneider or Siemens and indicate their origin, brand, model and product samples.
(2) The frequency control cabinet shall provide open communication protocols, be able to connect with various popular BA systems, and reserve enough DDC interfaces. And set up manual/automatic switch.
(3) The frequency conversion pump control cabinet shall provide the monitoring contact of the building control system on the operation status of the pump and fault alarm;
(4) The secondary wiring diagram of the frequency conversion control cabinet must be approved by the design.
6.3 Frequency converter
(1) The brand of frequency converter adopts Danfoss, ABB, Schneider.
(2) The technical characteristics of the frequency converter provided by the bidder should be referred to the requirements of the frequency converter later:
The pump group should be based on the actual water consumption of the system changes, that is, through the change of system pressure to change the power supply frequency of the pump, thereby changing the speed of the pump, to automatically adjust the water output of the pump.
7, heat exchanger unit automation control requirements
7.1 Temperature control: through the temperature of the secondary side, control the flow of the primary network by controlling the opening of the electric valve on the primary side, so as to maintain the set temperature at the outlet of the secondary network; automatically adjust the outlet temperature of the secondary network according to the outdoor temperature.
7.2 Pressure and differential pressure control: differential pressure control of supply and return water on the secondary side and return water pressure control on the secondary side.
7.3 Display and alarm: automatic microcomputerised monitoring and control of the import and export temperature, pressure, heat, flow rate and outdoor temperature of the primary and secondary networks, and automatic alarms for system overpressure, overheating of the motor, and lack of power supply phases.
7.4 Communication function: the controller of the unit has R485/232 standard communication interface and provides remote control software, which can be networked with BA system.
7.5 PLC controller LCD display, touch screen: with a display unit, the secondary side of the temperature, pressure, flow and outdoor temperature, the primary side of the electric temperature control valve opening; pump operation status, pump frequency, fault alarm and other major operating data, without personal management, simple operation, free to set the control temperature, over-temperature protection, power failure protection, water flow, low-pressure/loss-of-pressure protection, and so on.
8、Manual valves: Boon, TA, Danfoss;
8.1 Shut-off valve
The inlet and outlet shut-off valves on the unit must be welded ball valves.
The ball valves are integral welded parts, DN15-DN200 for handle type operation, >DN200 for worm gear type operation. Temperature resistance 180℃, design pressure PN25.
Seat and ball seal: Carbon reinforced PTFE;
Valve shaft seal: PTFE/graphite;
Valve body material: carbon steel,St.37.0;
Valve shaft and ball material: stainless steel ;
Ball body inner diameter ≥ DN100 ball valve inner diameter is cylindrical, in order to reduce water flow disturbance and reduce resistance;
Dimensions and functions in accordance with EN12266 and ISO5208; with ISO14001 and OHSAS18001 certification;
100% final inspection, service life 25~30 years, maintenance free.
8.2 Check Valve
Check valves are installed at the outlet of water pumps. Requirements for low resistance, low noise, good protection of the pump.
8.3 Safety valve
To prevent overpressure in the secondary side system, the safety valve is adjustable spring-type safety valve.
8.4 Water valve
Connection part of the water valve for the sealing butterfly valve, temperature resistance 120 degrees
9、 Dirt separator
First and second side are installed to remove dirt, dirt remover can remove particles greater than or equal to 2.0 mm, the dirt remover is equipped with a drain valve, the filter material is stainless steel. The body of the dirt separator has a differential pressure detection function.
10, temperature sensor, pressure transmitter,
10.1 Immersion temperature sensor
Sensor element: Pt1000;
Protection grade: IP54;
Temperature range: 0~140℃;
Sensor connection: two-wire system;
Installation: threaded connection;
Intrusion casing temperature range: 0~180℃;
Intrusion casing pressure: PN25;
The length of the sensor and the intrusion casing is selected by the installed pipe diameter.
10.2 Outdoor temperature sensor
Sensor element: Pt1000;
Protection grade: IP54;
Temperature range: -50~50℃;
Sensor connection: two-wire system;
Installation: the sensor is installed on the outdoor north wall, should avoid direct sunlight, more than 1.5m from the ground, avoid in the doors and windows directly above.
10.3 Pressure transmitter
Supply voltage: 24V DC;
Accuracy level: no more than +/-0.5% FS;
Output signal: 3-wire system, 0-10V;
Protection grade: IP65;
Measuring range: 0~16bar;
Response time: ≤4ms;
Ambient temperature: -40~85℃.
11、 Thermometer and pressure gauge
The thermometer adopts bimetallic thermometer, with the range of 0-150 ℃ on the primary side and 0-100 ℃ on the secondary side, and the accuracy level is not more than 1.5.
Pressure gauge for the spring tube pressure gauge, in MPa units, 0-1.6MPa range, accuracy level of not more than 1.6 level.
12、 Solenoid valve
Solenoid valve is normally closed type, coil protection grade IP67.
